Intra-arterial Selective Hypothermic Magnesium Sulfate Infusion in Combination With Endovascular Thrombectomy in Acute Ischemic Stroke

Condition(s) studied

Investigational drug(s) / intervention(s)

Endovascular thrombectomy combination with selective intra-arterial hypothermic magnesium sulfate infusion (350 ml).: According to patient's weight, magnesium sulfate (MgSO4) will be diluted to 350 ml 4°C saline solution (0.6μmol/kg/ml). During the thrombectomy procedure, a micro-catheter will be advanced until it reaches beyond the clot responsible for the ischemic symptoms, then cold 50 ml MgSO4 solution will be infused into the ischemic territory at 10 ml/min through the micro-catheter. After that, thrombectomy with a stent retriever will be performed to recanalize the occluded vessel as soon as possible. Immediately after successful thrombectomy, cold MgSO4 solution will be re-infused into the ischemic brain tissue through the catheter at a rate of 30 ml/min for 10 min. Note: The pre-planned weight-tailored magnesium solution could not be prepared intraoperatively in phase 1 due to unavailable emergency pharmacy workflow. All 9 patients received uniform 20.29 mmol/L perfusate, with only infusion volume escalated.

Endovascular thrombectomy combination with selective intra-arterial hypothermic magnesium sulfate infusion (500 ml).: According to patient's weight, magnesium sulfate (MgSO4) will be diluted to 500 ml 4°C saline solution (0.6μmol/kg/ml). During the thrombectomy procedure, a micro-catheter will be advanced until it reaches beyond the clot responsible for the ischemic symptoms, then cold 50 ml MgSO4 solution will be infused into the ischemic territory at 10 ml/min through the micro-catheter. After that, thrombectomy with a stent retriever will be performed to recanalize the occluded vessel as soon as possible. Immediately after successful thrombectomy, cold MgSO4 solution will be re-infused into the ischemic brain tissue through the catheter at a rate of 30 ml/min for 10 min. Then pause for 5 min, followed by another 5 min of infusion at the original rate.Note: The pre-planned weight-tailored magnesium solution could not be prepared intraoperatively in phase 1 due to unavailable emergency pharmacy workflow. All 9 patients received uniform 20.29 mmol/L perfusate, with only infusion volume escalated.

Endovascular thrombectomy combination with selective intra-arterial hypothermic magnesium sulfate infusion (650 ml).: According to patient's weight, magnesium sulfate (MgSO4) will be diluted to 650 ml 4°C saline solution (0.6μmol/kg/ml). During the thrombectomy procedure, a micro-catheter will be advanced until it reaches beyond the clot responsible for the ischemic symptoms, then cold 50 ml MgSO4 solution will be infused into the ischemic territory at 10 ml/min through the micro-catheter. After that, thrombectomy with a stent retriever will be performed to recanalize the occluded vessel as soon as possible. Immediately after successful thrombectomy, cold MgSO4 solution will be re-infused into the ischemic brain tissue through the catheter at a rate of 30 ml/min for 10 min. Then pause for 5 min, followed by intermittent infusion at the original rate for another 5 min twice. The interval between two times is also 5 min.Note: The pre-planned weight-tailored magnesium solution could not be prepared intraoperatively in phase 1.All 9 patients received uniform 20.29 mmol/L perfusate.

Endovascular thrombectomy: Endovascular thrombectomy

Phase 2 Fixed-Volume Concentration-Escalation Cohort: This unenrolled phase 2 cohort uses a fixed 650 mL maximum infusion volume with six ascending magnesium concentrations: 20.29, 22.54, 25.36, 28.98, 33.81, 40.57 mmol/L. Each tier is mixed by diluting one 5 g magnesium stock into 1000/900/800/700/600/500 mL pre-cooled saline. After confirming safe magnesium levels, we will adopt the registry's weight-based formulation. Infusion protocols match phase 1, and this two-stage design is approved under IRB amendment No.XYFY2025-KL360-02

Study summary

The primary objective of this study is to estimate the safety and effectiveness of selective intra-arterial hypothermic magnesium sulfate infusion after endovascular thrombectomy in patients with acute ischemic stroke.

Addendum regarding phase 1 dosing implementation and planned phase 2 design:

This integrated phase 1/2 trial originally planned weight-individualized magnesium perfusate calculated as Target Mg (μmol/mL) = 0.6 × patient body weight. During phase 1 recruitment, no dedicated emergency pharmacy fast-track compound workflow existed for urgent EVT procedures, which would cause reperfusion delay if individualized mixing was performed intraoperatively. Therefore, a uniform fixed magnesium concentration of 20.29 mmol/L was adopted as a temporary operational solution for all 9 phase 1 participants, with dose escalation only performed by increasing total infusion volume (350/500/650 mL). For the upcoming phase 2 cohort, we will retain the fully safe 650 mL maximum infusion volume and conduct independent magnesium concentration escalation across six ascending tiers: 20.29, 22.54, 25.36, 28.98, 33.81, and 40.57 mmol/L. These concentrations are prepared by diluting the standard 5 g magnesium stock into 1000 mL, 900 mL, 800 mL, 700 mL, 600 mL, and 500 mL pre-cooled normal saline respectively. After defining the maximum tolerated magnesium concentration tier, the original weight-tailored compounding formula will be fully implemented for subsequent efficacy cohorts. All protocol adjustments have received institutional review board amendment approval.

Eligibility

Primary outcome measure(s)

• Mortality at 90 days — 90 days after intra-arterial hypothermic magnesium sulfate infusion
• Effectiveness evaluation indicators: — 90 days after intra-arterial hypothermic magnesium sulfate infusion
  Percentage of subjects with 90 days of functional independence (defined as mRS 0-2) (%) Evaluation time: 90 d (±14 d) after surgery

Trial sites (1)

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